Is the thermal resistance coefficient of high-power LEDs constant?

2007 ◽  
Author(s):  
Lalith Jayasinghe ◽  
Tianming Dong ◽  
Nadarajah Narendran
Keyword(s):  
Thermal Resistance ◽  
High Power ◽  
Resistance Coefficient

Improved Heat Dissipation and Optical Performance of High-power LED Packaging with Sintered Nanosilver Die-attach Material

2010 ◽  
Vol 2010 (DPC) ◽  
pp. 001585-001605 ◽  
Author(s):  
Paul Panaccione ◽  
Tao Wang ◽  
Guo-Quan Lu ◽  
Xu Chen ◽  
Susan Luo
Keyword(s):  
Thermal Resistance ◽  
High Power ◽  
Heat Removal ◽  
High Current ◽  
Die Attach ◽  
High Power Led ◽  
Silver Epoxy ◽  
The Difference ◽  
Nanosilver Paste ◽  
The Impact

Heat removal in packaged high-power light-emitting diode (LED) chips is critical to device performance and reliability. Thermal performance of LEDs is important in that lowered junction temperatures extend the LED's lifetime at a given photometric flux (brightness). Optionally, lower thermal resistance can enable increased brightness operation without exceeding the maximum allowable Tj for a given lifetime. A significant portion of the junction-to-case thermal resistance comes from the joint between chip and substrate, or the die-attach layer. In this study, we evaluated three different types of leading die-attach materials; silver epoxy, lead-free solder, and an emerging nanosilver paste. Each of the three was processed via their respective physical and chemical mechanisms: epoxy curing by cross-linking of polymer molecules; intermetalic soldering by reflow and solidification; and nanosilver sintering by solid-state atomic diffusion. High-power LED chips with a chip area of 3.9 mm2 were attached by the three types of materials onto metalized aluminum nitride substrates, wire-bonded, and then tested in an electro-optical setup. The junction-to-heatsink thermal resistance of each LED assembly was determined by the wavelength shift methodology, described in detail in this paper. We found that the average thermal resistance in the chips attached by the nanosilver paste was the lowest, and it is the highest from the chips attached by the silver epoxy: the difference between the two was about 0.7°C/W, while the difference between the sintered and soldered was about 0.3°C/W. The lower thermal resistance in the sintered joints is expected to significantly improve the photometric flux from the device. Simple calculations, excluding high current efficiency droop, predict that the brightness improvement could be as high as 50% for the 3.9 mm2 chip. The samples will be functionally tested at high current, in both steady-state and pulsed operation, to determine brightness improvements, including the impact of droop. Nanosilver die-attach on a range of chip sizes up to 12 mm2 are also considered and discussed.

Experimental Study of Thermal Resistance Measurement for High Power Laser Diode Array

2010 ◽  
Vol 47 (11) ◽  
pp. 112501
Author(s):  
辛国锋 Xin Guofeng ◽  
沈力 Shen Li ◽  
皮浩洋 Pi Haoyang ◽  
瞿荣辉 Qu Ronghui ◽  
蔡海文 Cai Haiwen ◽  
...  
Keyword(s):  
Experimental Study ◽  
Thermal Resistance ◽  
Laser Diode ◽  
High Power ◽  
Resistance Measurement ◽  
Diode Array ◽  
High Power Laser ◽  
Power Laser ◽  
Laser Diode Array ◽  
High Power Laser Diode

Thermal Resistance Analysis and Simulation of IGBT Module with High Power Density

2013 ◽  
Vol 303-306 ◽  
pp. 1902-1907 ◽  
Author(s):  
Yi Bo Wu ◽  
Guo You Liu ◽  
Ning Hua Xu ◽  
Ze Chun Dou
Keyword(s):  
Thermal Resistance ◽  
Power Density ◽  
High Power ◽  
Resistance Management ◽  
Equivalent Circuit Model ◽  
Element Model ◽  
Equivalent Model ◽  
High Power Density ◽  
Power Module ◽  
Igbt Module

As the IGBT power modules have promising potentials in the application of the field of traction or new energy, the higher power density and higher current rating of the IGBT module become more and more attractive. Thermal resistance is one of the most important characteristics in the application of power semiconductor module. A new 1500A/3300V IGBT module in traction application is developed successfully by Zhuzhou CSR Times Electric Co., Ltd (Lincoln). Thermal resistance management of this IGBT module with high power density is performed in this paper. Based on thermal nodes network, an equivalent circuit model for thermal resistance of power module is highlighted from which the steady state thermal resistance can be optimized by theoretical analysis. Furthermore, thermal numerical simulation of 1500A/3300V IGBT module is accomplished by means of finite element model (FEM). Finally, the thermal equivalent model of the IGBT module is verified by simulation results.

scholarly journals Research on thermal resistance Rthj-c of high power semiconductor light sources

2019 ◽  
Author(s):  
Krzysztof Baran ◽  
Henryk Wachta ◽  
Marcin Leśko ◽  
Antoni Różowicz
Keyword(s):  
Thermal Resistance ◽  
High Power ◽  
Light Sources ◽  
Power Semiconductor

scholarly journals Analysis and Prediction of Thermal Resistance for High Power LED Using GA-SVR

2012 ◽  
Vol 4 ◽  
pp. 153-160
Author(s):  
De Huai Zeng ◽  
Yuan Liu ◽  
Li Li ◽  
De Gui Yu ◽  
Gang Xu
Keyword(s):  
Service Life ◽  
Thermal Resistance ◽  
High Power ◽  
Thermal Characteristics ◽  
Junction Temperature ◽  
Support Vector ◽  
Mean Squared Errors ◽  
Absolute Relative Error ◽  
High Power Led ◽  
Key Factor

With the development of high power LED technology, junction temperature as a key factor constrains the performance and the service life of LED, and the main parameter of junction temperature is thermal resistance. Therefore, how to measure the thermal resistance of high power LED quickly and accurately plays an important part in improving the performance and the service life of LED. In this paper the accurate and fast measurement equipment was applied to study the thermal characteristics of high power LED. The forward-voltage based method was conducted to measure the junction temperature of high power. Then, support vector regression (SVR) combined with genetic algorithm (GA) for its parameter optimization, was proposed to establish a model to predict the thermal resistance of high power LED. The prediction performance of GA-SVR was compared with those of BPNN model. The result demonstrated that the estimated errors GA-SVR models, such as Mean Absolute Relative Error (MARE) and Root Mean Squared Errors (RMSE), all are smaller than those achieved by the BPNN applying identical samples.

Effect of Phosphor Encapsulant on the Thermal Resistance of a High-Power COB LED Module

2013 ◽  
Vol 3 (7) ◽  
pp. 1148-1154 ◽  
Author(s):  
Eveliina Juntunen ◽  
Olli Tapaninen ◽  
Aila Sitomaniemi ◽  
Veli Heikkinen
Keyword(s):  
Thermal Resistance ◽  
High Power

Improved Heat Dissipation and Optical Performance of High-Power LED Packaging with Sintered Nanosilver Die-Attach Material

2010 ◽  
Vol 7 (3) ◽  
pp. 164-168 ◽  
Author(s):  
Paul Panaccione ◽  
Tao Wang ◽  
Xu Chen ◽  
Susan Luo ◽  
Guo-Quan Lu
Keyword(s):  
Thermal Resistance ◽  
High Power ◽  
Heat Removal ◽  
High Current ◽  
Die Attach ◽  
High Power Led ◽  
Silver Epoxy ◽  
The Difference ◽  
Nanosilver Paste ◽  
The Impact

Heat removal in packaged high-power light-emitting diode (LED) chips is critical to device performance and reliability. Thermal performance of LEDs is important in that lowered junction temperatures extend the LED's lifetime at a given pho-tometric flux (brightness). Optionally, lower thermal resistance can enable increased brightness operation without exceeding the maximum allowable Tj for a given lifetime. A significant portion of the junction-to-case thermal resistance comes from the joint between chip and substrate, or the die-attach layer. In this study, we evaluated three different types of leading die-attach materials; silver epoxy, lead-free solder, and an emerging nanosilver paste. Each of the three was processed via their respective physical and chemical mechanisms: epoxy curing by cross-linking of polymer molecules; intermetalic soldering by reflow and solidification; and nanosilver sintering by solid-state atomic diffusion. High-power LED chips with a range of chip areas from 3.9 mm2 to 9.0 mm2 were attached by the three types of materials onto metalized aluminum nitride substrates, wire-bonded, and then tested in an electro-optical setup. The junction-to-heatsink thermal resistance of each LED assembly was determined by the wavelength shift methodology. We found that the average thermal resistance in the chips attached by the nanosilver paste was the lowest, and it was highest from the chips attached by the silver epoxy. For the 3.9 mm2 die, the difference was about 0.6°C/W, while the difference between the sintered and soldered was about 0.3°C/W. The lower thermal resistance in the sintered joints is expected to significantly improve the photometric flux from the device. Simple calculations, excluding high current efficiency droop, predict that the brightness improvement could be as high as 50% for the 3.9 mm2 chip. The samples will be functionally tested at high current, in both steady-state and pulsed operation, to determine brightness improvements, including the impact of droop. Nanosilver die-attach on a range of chip sizes up to 12 mm2 are also considered and discussed.

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